We investigate the effects of political institutions on economic growth. We specifically explore this relationship while controlling for heterogeneity and model uncertainty. We use threshold regression (Hansen 2000) to search for possible nonlinearities and/or interaction effects with respect to political institutions. We also implement a novel approach to account for theory uncertainty by applying Bayesian model averaging in the threshold regression context. We find that less democratic countries, specifically those with less competitiveness in executive recruitment, follow a different growth process than those with higher competitiveness.